Photo-electric device



1,628 822 May 17 1927. T. w. CASE PHOTO ELECTRIC DEVICE Filed Dec. 19. 1921 Fly.-

Patent d May 17, 1921.-

umrso s ra'rss PATENT OFFICE.-

THEODORE WIIiLABD CASE, OF SGIIIO, NEW YORK, ABBIGNOR TO CASEjBESEABCHI' LABORATORY INCORPORATED, OF AUBURN, YORK, A CORPORATION 01' NEW rnoro-mnc'rarc DEVICE. I

Application flied December 19, 1921. Serial No. 523,6?

This invention relates to a certain new and useful photo-electric device.

The main object of the invention is to produce a device sensitive to light, and capable of reacting to variations of light 1ntensity, and of indicating such variatlons in a manner capable of physical interpretation, and incidently adapted for use in determining or testing the 1 light reactive quality of substances or materials.

The invention is adapted for various uses and its operation and construction will be understood from the followingv description taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic illustration of an embodiment of my invention.

Figure 2 is a diagrammatic illustration of a different embodiment of my invention.

Figure 3 is a diagrammatic illustration of a further and different embodiment of my invention.

It is known that if a heated filament and a plate, or other electrode, be confined in spaced relation within a vacuum bulb or vessel, the heated filament being connected to the negative side of a suitable source of potential, and the plate or other electrode connected to the positive side of the source of potential, that a thermoelectric current will flow from the filament to the plate or other electrode, and my invention takes advantage of this known operation of a device of the character described, in that in combination with such a structure I place within the vacuum bulb or vessel in any suitable position therein, a photo-electric material. This photo-electric material may, as shown vin Figure 1, constitute or form a coating for a grid, or third electrode 3- positioned between the filament --1 and the plate 2-, all of which electrodes are confined within the bulb 4- which, as stated, is preferably maintained under high vacuum altho for certain purposes an inert gas may be introduced into the bulb in desired quantities.

The filament -1- may be heated in anyconstruction, a thermo-electric current will flow under normal conditions from the fil-' ament -1 to the plate -2.

Many photo-electric'materials are rich in negative electrons, and emit negative particles or electrons under the influence of light. Other'photo-electric materials may emit positive particles under the influence of light. Under either circumstance, it is found that a variation in light intensity either impedes or accellerates the thermo-,'

electric current flowing between the filament and the plate, and whether the flow of such current is impeded or accelerated depends upon the character of the photo-electric material.

The photo-electric material may be variously positioned within the device, and in various relative arrangements with respect to the filament -1- and the plate --2. In Figure 1 the (grid 3-- is shown, which may be compose of or may include a coating or a partial coating of photo-electric ma terial, and altho this grid need have no external connections of any character in order to efl'ect the operation described, it may A suitable indicating device -8- is shown in the circuit between the filament and plate, for showing variations of the current flowing in that circuit, as effected by variations in the intensity of the lightto which the photo-electric material is subjected.

Variations in light intensity to which the photo-electric material is subjected will efect corresponding changes in the thermoelectric current flowing in the circuit, including the filament --1 and the plate -2 as a result probably of. variations in the electrons thrown oil by the said photoelectric material and consequent change of charge near the thermo-electrio current. With this invention a large thermo-electric current variation may be obtained with very small light exposure. U

more or less the etlicient results of the in-,

vention, and that the specific structures shown are illustrative of embodiments of the invention without intention of restricting the scope of the claims to any particular detailed form, arrangement or construction of the device, except as specifically set forth in the claims hereto appended.

I claim:

1. A thermo-electric device comprising a bulb, a pair of spaced electrodes within the bulb, means for maintaining one-of the electrodes heated, means for causing a thermoelectric current to flow between the electrodes, and a substance that emits electrons in substantial accordance with the intensity of the light to which it is subjected disposed in such a position with respect to the path of the thermo-electric current between the electrodes that the emitted electrons atl'ect the conductivity of such path, and thereby vary the thermo-electric current in substantial accordance with the intensity of the light to which the substance is subjected.

'2. A thermo-electric device comprising a bulb, a'pair of spaced electrodes within the bulb, means for maintaining one of the electrodes heated, means for causing a thermoelectric current to flow between the electrodes, and a substance that emits electrons in substantial accordance with the intensity of the light to which it is subjected, said substance being Without effective electrical connections, and being disposed within the bulb in such a position that the emitted electrons affect the conductivity of the space between the electrodes and thereby vary the thermo-electric current in substantial accordance with light waves.

3. A thermo-electric device comprising a bulb enclosing a cathode and an anode, means for heating the cathode, means for causing a thermo-electric current to flow between the electrodes, and a photo-active material which emits electrons in accordance with the. intensity of the light to which it is subjected disposed in such a position with respect to the path of the thermoelectric current between the electrodes that the electrons emitted act to vary the thermoelectric current in substantial accordance with the intensity of the light to which the photo-active material is subjected.

In witness whereof I have hereunto set my hand.

THEODORE WILLARD CASE. 

